538 



COZENS 



CRAB 



flanks, 

 and fur 



The coypu is much hunted for its flesh 

 The latter is best known under the 



Coypu (Myopotamus coypu), 



Spanish name of Nutria, and forms an important 

 article of commerce. 



Cozens* JOHN ROBERT, water-colour painter, 

 was born in England in 1752. He was instructed 

 by his father, Alexander Cozens, also known as an 

 artist in water-colours, who was one of the two 

 natural sons of Peter the Great, by a woman from 

 Deptford who accompanied the Czar to Russia. In 

 1776 he visited Switzerland, with R. Payne Knight, 

 and in 1783 returned from an extended tour in Italy 

 with William Beckford, who commissioned many 

 of the washed drawings which he then executed. 

 Among his English subjects are some fine studies 

 of trees made in Windsor Forest. In 1794 the 

 artist's mind gave way, and in his later days he 

 was befriended by Sir George Beaumont and Dr 

 Munro. The date of his death has been usually 

 stated as 1799, but there is reason to believe that 

 he was alive after 1801. The great qualities of his 

 art have commanded the enthusiasm of brother- 

 painters. Turner and Girtin copied his drawings, 

 and Constable pronounced that ' his works were all 

 poetry,' that he was 'the greatest genius that ever 

 touched landscape.' He to some extent extended 

 the very limited colour-scheme of previous painters 

 in the medium, introducing greater force and 

 variety of tinting ; and he sulistituted for their 

 topographical treatment of landscape a rendering 

 more imaginative and more perceptive of the 

 delicacies of atmospheric effect. In composition, 

 his works are singularly large and harmonious, and 

 they evince an especial sympathy for nature in her 

 moods of placid sublimity. There is a fine series 

 of his Avorks in the British Museum Print Room. 



Crab, a popular name legitimately applied to 

 any of the short-tailed (Brachyura) division of 

 decapod Crustaceans (q.v. ). The body is usually 

 short and compressed ; the abdomen is short and 

 is tucked up beneath the relatively large cephalo- 

 thorax ; there are 1 to 4 reduced abdominal 

 appendages, but seldom any tail-paddles ; the 

 antennae are short. In the common Shore-crab 

 (Carcinus mcenas) the carapace is a wide shield, 

 broader than long, and bent inwards at the sides ; 

 the eyes are stalked, and He as usual above and in 

 front of the antennules, though apparently rather 

 external to them ; the antennules have the ear-sac 

 lodged in their dilated base ; the bases of the 

 antennse are immovable, and the opening of the 

 excretory organ at their base has a curious movable 

 plate. The hindmost of the foot-jaws or maxilli- 

 pedes is in part expanded into a broad plate which 

 covers the neighbouring appendages. The great 

 claws are generally larger in the male than in the 

 female, and thus the market value of the male 

 Edible Crab ( Cancer pagurus ) is said to be five 

 times as great as that of the female. The reduced 



abdominal appendages of crabs are solely used for 

 reproductive purposes. The two anterior pairs are 

 copulatory in the males ; those that persist in the 

 females have the eggs attached to them. The 

 abdomen is always larger and broader in the 

 females. The nervous system is peculiar in the 

 centralisation of the thoracic ganglia into a single 

 mass. The alimentary, circulatory, and excretor^ 

 svstems do not present any important peculiarities. 

 The gills are always fewer than in the crayfish, 

 never exceeding nine on each side. The gill-cavity 

 is large, especially in the land -crabs. In the 

 common shore-crab, the larva leaves the egg as a 

 zosea, after repeated moults becomes a sort of 

 hermit-crab-like form known as a Megalopa, and 

 gradually with broadening shield, loss of abdominal 



Great Crab (Cancer pagurus). 



appendages, bending up of the abdomen, and modi- 

 fication of the anterior limbs becomes a miniature 

 adult. 



General Life. Crabs feed chiefly on other animals 

 both alive and dead. The Swimming Crabs 

 ( Portunus ) e. g. P. pelagicus, attack fishes. Cardi- 

 soma carnifex, found in the mangrove swamps 

 of the West Indies, is fond of the fruit of a species 

 of Anona, but is also notorious for burrowing 

 in the cemeteries. The well-known Land-crab 

 ( Gecarcinus ruricola ) damages sugar-canes. Many 

 crabs are very rapid runners, especially the sand 

 and land forms ; others are powerful burrowers 

 e.g. the Calling Crab ( Gelasimus ), which has one 

 of its great claws much exaggerated, and carried 

 during locomotion over its head in such a way that 

 it looks as if it were beckoning ; others again are 

 expert swimmers e.g. our British pelagic Polybius 

 henslowii, which has a light shell, and four of its 

 thoracic appendages flattened for swimming. In 

 regard to respiration it is worth noticing that the 

 land-crabs are so far terrestrial that they are 

 liable to be drowned in water. The male crabs 

 are usually larger, and sometimes fight with one 

 another as well as with other species. In some 

 cases (Gelasimus) the bright colour is only 

 acquired at the period of reproductive maturity. 

 The sexes of the common Shore-crab ( Carcinus 

 mcenas} are said' to unite just after the female has 

 moulted her hard shell. In all but the land-crabs 

 the female carries about the eggs till they are 

 hatched. 



Habitat. Almost all crabs are strictly marine 

 forms, and the majority frequent shallow water. 

 Among the terrestrial forms the best known are 

 the species of Gecarcinus, swiftly moving nocturnal 

 crabs in tropical regions of both hemispheres, 

 chiefly vegetarian in their diet, migrating in 

 companies to the sea for egg-laying purposes. 

 The genus Ocypoda includes some land forms, 

 and some which produce a shrill noise by rubbing 

 the ridged surface of the second-last joint of 



